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High Energy Physics - Theory

Title:Bulk supertranslation memories: a concept reshaping the vacua and black holes of general relativity

Abstract: The memory effect is a prediction of general relativity on the same footing
as the existence of gravitational waves. The memory effect is understood at
future null infinity as a transition induced by null radiation from a
Poincaré vacuum to another vacuum. Those are related by a supertranslation,
which is a fundamental symmetry of asymptotically flat spacetimes. In this
essay, I argue that finite supertranslation diffeomorphisms should be extended
into the bulk spacetime consistently with canonical charge conservation. It
then leads to fascinating geometrical features of gravitational Poincaré
vacua. I then argue that in the process of black hole merger or gravitational
collapse, dramatic but computable memory effects occur. They lead to a final
stationary metric which qualitatively deviates from the Schwarzschild metric.